Eroare de compilare: main.cpp: In function 'int minCost()': main.cpp:157:9: warning: unused variable 'nr' [-Wunused-variable] 157 | int nr = 0; | ^~ In file included from /usr/include/c++/10/string:48, from /usr/include/c++/10/bits/locale_classes.h:40, from /usr/include/c++/10/bits/ios_base.h:41, from /usr/include/c++/10/ios:42, from /usr/include/c++/10/istream:38, from /usr/include/c++/10/sstream:38, from /usr/include/c++/10/complex:45, from /usr/include/c++/10/ccomplex:39, from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:54, from main.cpp:1: /usr/include/c++/10/bits/stl_function.h: In instantiation of 'constexpr bool std::less<_Tp>::operator()(const _Tp&, const _Tp&) const [with _Tp = nod]': /usr/include/c++/10/bits/predefined_ops.h:194:23: required from 'bool __gnu_cxx::__ops::_Iter_comp_val<_Compare>::operator()(_Iterator, _Value&) [with _Iterator = __gnu_cxx::__normal_iterator<nod*, std::vector<nod, std::allocator<nod> > >; _Value = nod; _Compare = std::less<nod>]' /usr/include/c++/10/bits/stl_heap.h:139:48: required from 'void std::__push_heap(_RandomAccessIterator, _Distance, _Distance, _Tp, _Compare&) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<nod*, std::vector<nod, std::allocator<nod> > >; _Distance = long int; _Tp = nod; _Compare = __gnu_cxx::__ops::_Iter_comp_val<std::less<nod> >]' /usr/include/c++/10/bits/stl_heap.h:215:23: required from 'void std::push_heap(_RAIter, _RAIter, _Compare) [with _RAIter = __gnu_cxx::__normal_iterator<nod*, std::vector<nod, std::allocator<nod> > >; _Compare = std::less<nod>]' /usr/include/c++/10/bits/stl_queue.h:651:16: required from 'void std::priority_queue<_Tp, _Sequence, _Compare>::push(std::priority_queue<_Tp, _Sequence, _Compare>::value_type&&) [with _Tp = nod; _Sequence = std::vector<nod, std::allocator<nod> >; _Compare = std::less<nod>; std::priority_queue<_Tp, _Sequence, _Compare>::value_type = nod]' main.cpp:131:26: required from here /usr/include/c++/10/bits/stl_function.h:386:20: error: no match for 'operator<' (operand types are 'const nod' and 'const nod') 386 | { return __x < __y; } | ~~~~^~~~~ main.cpp:81:10: note: candidate: 'bool nod::operator<(nod&)' (near match) 81 | bool operator < (nod& aux) { | ^~~~~~~~ main.cpp:81:10: note: conversion of argument 1 would be ill-formed: In file included from /usr/include/c++/10/string:48, from /usr/include/c++/10/bits/locale_classes.h:40, from /usr/include/c++/10/bits/ios_base.h:41, from /usr/include/c++/10/ios:42, from /usr/include/c++/10/istream:38, from /usr/include/c++/10/sstream:38, from /usr/include/c++/10/complex:45, from /usr/include/c++/10/ccomplex:39, from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:54, from main.cpp:1: /usr/include/c++/10/bits/stl_function.h:386:20: error: binding reference of type 'nod&' to 'const nod' discards qualifiers 386 | { return __x < __y; } | ~~~~^~~~~ In file included from /usr/include/c++/10/bits/stl_algobase.h:64, from /usr/include/c++/10/bits/char_traits.h:39, from /usr/include/c++/10/ios:40, from /usr/include/c++/10/istream:38, from /usr/include/c++/10/sstream:38, from /usr/include/c++/10/complex:45, from /usr/include/c++/10/ccomplex:39, from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:54, from main.cpp:1: /usr/include/c++/10/bits/stl_pair.h:489:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator<(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)' Non zero exit status: 1